Hidden soft plug under rear main cap on a 340

[soccernut43]

Does anybody have any instruction on removing the soft plug under the rear main cap on a 340 engine?  Where does is go to once removed?  And what's the correct way to install one?  What is the recommended soft plug kit to use? I've read reviews on some and there aren't many highly recommened.

As always thank you for your help.

Mike

[Rich G.]

Soft plug? Not sure what you're talking about. Are you talking about the rear main seal?

[soccernut43]

I hope I'm wrong but read some posts where they said one was here where the all thread is.

[soccernut43]

The kit from Summit showing the replacement soft plugs shows I got them all.  I'm hoping so.

[soccernut43]

Unfortunately this picture shows something on the other side.  Not sure if it needs to be removed or not if engine is going to be cleaned by a machine shop or not.   

[1 Wild R/T]

There is a plug there... It's been a long time since I played with a small block but I seem to remember the plug can be driven out by using a rod through the oil pressure sending unit hole.... I believe that passage goes completely through the block & has a few steps getting larger toward the main cap... The plug forces oil to go through the oil filter, the two passages (into & out of) the oil filter intersect that passage so if the plug is not present the oil bypasses the filter...

If the plug isn't driven deep enough the oil flow is blocked before the filter... To deep & it gets blocked after the filter.... The proper depth & it is forced to go through the filter then it going to the gallery supplying the the main bearings..

[soccernut43]

I looked at the Summit soft plugs and threaded plugs and unless the picture is wrong it doesn't take this one into account. Interesting the picture I post above yours gives measurements how deep the plug goes.  Now I'm wondering whether to leave it or not.  With my luck that's the plug that would give me problems lol.

[1 Wild R/T]

I'd leave it unless the engine has been fed metal from a failed cam or spun bearing... That kind of debris tends to hide in areas like the edge of a soft plug then pop free while the engine is running causing damage... But if the engine is clean leave it alone...

[soccernut43]

I'm hoping I can.  But I'm not sure what the machine shop will use to clean the block and how it might affect "that" plug lol.